High-speed audio data transmission method and apparatus

ABSTRACT

An audio data transmission method includes encapsulating, based on a physical layer frame header, a protocol data unit (PDU) including audio data, to obtain an audio data packet, where the physical layer frame header is modulated using a first digital modulation scheme, the PDU is modulated using a second digital modulation scheme, a value of a modulation rate of the first digital modulation scheme is equal to a value of a data transmission rate, and a value of a modulation rate of the second digital modulation scheme is less than the value of the data transmission rate, and sending the audio data packet on a BLUETOOTH low energy (BLE) physical channel at the data transmission rate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2019/070803, filed on Jan. 8, 2019, which claims priority toChinese Patent Application No. 201810151616.7, filed on Feb. 14, 2018,both of which are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present application relates to the communications field, and inparticular, to an audio data transmission method and apparatus.

BACKGROUND

With rapid development of mobile communications technologies, portabledevices such as mobile phones and tablet computers have becomenecessities in people's daily life, and a BLUETOOTH technology hasbecome a standard configuration for these portable devices.

Listening to BLUETOOTH music based on a BLUETOOTH technology is one ofthe most valuable applications of BLUETOOTH. The advanced audiodistribution profile (A2DP) is used for an application to implement afunction of playing the BLUETOOTH music. Based on a conventionalBLUETOOTH technology, audio data is transmitted using an asynchronousconnection-oriented logical transport (ACL) connection between devices,and currently, a BLUETOOTH device can provide a maximum physical rate of3 megabits per second (Mb/s).

However, limited by a physical rate in a current BLUETOOTHspecification, BLUETOOTH audio is transmitted in a lossy compressionmode with a relatively high compression ratio, and transmission ofhigher-definition audio data cannot be supported.

SUMMARY

Embodiments of this application provide an audio data transmissionmethod and apparatus, to increase an audio data transmission rate,thereby supporting transmission of higher-definition audio data.

According to a first aspect, an embodiment of this application providesan audio data transmission method. The method includes encapsulating,based on a physical layer frame header, a protocol data unit (PDU)including audio data, to obtain an audio data packet, where the physicallayer frame header is modulated using a first digital modulation scheme,the PDU is modulated using a second digital modulation scheme, a valueof a modulation rate of the first digital modulation scheme is equal toa value of a data transmission rate, and a value of a modulation rate ofthe second digital modulation scheme is less than the value of the datatransmission rate, and sending the audio data packet on a BLUETOOTH lowenergy (BLE) physical channel at the data transmission rate.

In the foregoing method, the physical layer frame header is modulatedusing the first digital modulation scheme, and the PDU is modulatedusing the second digital modulation scheme. Because the physical layerframe header and the PDU are modulated using two different modulationschemes, the modulation rate of the modulation scheme for the PDU islower than the data transmission rate, that is, a same symbol can carrymore bits, thereby increasing an audio data transmission rate.Therefore, transmission of high-definition audio data can be supported.

In a possible design, the method further includes generating amodulation scheme identifier of the BLE physical channel, based on themodulation scheme identifier, determining that the physical layer frameheader uses the first digital modulation scheme, and determining thatthe PDU uses the second digital modulation scheme, and sending themodulation scheme identifier.

In the foregoing method, the modulation scheme used by the physicallayer frame header and the modulation scheme used by the PDU can bedetermined based on the modulation scheme identifier. In this way, areceiving device can demodulate the PDU based on the determinedmodulation scheme. In a possible design, the data transmission rate is Ntimes the modulation rate of the second digital modulation scheme, whereN is an integer greater than 1.

In the foregoing method, high-definition audio data can be transmittedon the BLE physical channel at the data transmission rate based on thePDU that is modulated using the second digital modulation scheme.

In a possible design, the PDU includes a control layer frame header anda payload, the payload is used to carry the audio data, and the controllayer frame header includes indication information used to indicate alength of the audio data.

In the foregoing method, the receiving device can verify, based on theindication information for the length of the audio data in the controllayer frame header, whether the received audio data is complete.

In a possible design, a bandwidth of the BLE physical channel is 2megahertz (MHz), or a bandwidth of the BLE physical channel is 4 MHz,and the physical channel having the bandwidth of 4 MHz is formed bycombining two adjacent physical channels each having a bandwidth of 2MHz.

In the foregoing method, the audio data can be transmitted at differentdata transmission rates using bandwidths of different physical channels.

In a possible design, the first digital modulation scheme includesGaussian frequency-shift keying (GFSK), and the second digitalmodulation scheme includes differential quadrature phase-shift keying(DQPSK) or 8-differential phase shift keying (8DPSK).

In the foregoing method, the first digital modulation scheme is theGFSK, and the second digital modulation scheme is the DQPSK or the8DPSK. In this way, compatibility between a BLE mode and an enhanceddata rate (EDR) mode is implemented, and power consumption can bereduced while the audio data is transmitted at a high speed.

In a possible design, a modulation factor of the GFSK ranges from 0.45to 0.55.

In the foregoing method, the modulation factor of the GFSK falls withinthe range from 0.45 to 0.55 such that an original hardware device can beused, thereby saving hardware resources.

In a possible design, an audio connection end command is sent on the BLEphysical channel.

In the foregoing method, a sending device is disconnected from thereceiving device using the audio connection end command, to avoid powerconsumption of the sending device and the receiving device, and avoid awaste of resources.

In a possible design, the method further includes querying a codecparameter using the logical link control and adaptation protocol(L2CAP), where the codec parameter includes a coding parameter of theaudio data, and encoding original audio data based on the codingparameter, to obtain the audio data.

In the foregoing method, the coding parameter is queried using theL2CAP, and the original audio data is encoded, to ensure normal audioplay.

According to a second aspect, an embodiment of this application providesan audio data transmission method. The method includes receiving anaudio data packet on a BLE physical channel, where the audio data packetincludes a physical layer frame header and a PDU, and demodulating thephysical layer frame header using a first digital modulation scheme, anddemodulating the PDU using a second digital modulation scheme, to obtainaudio data, where a value of a modulation rate of the first digitalmodulation scheme is equal to a value of a data transmission rate, and avalue of a modulation rate of the second digital modulation scheme isless than the value of the data transmission rate.

In the foregoing method, the audio data packet is received on the BLEphysical channel, the physical layer frame header is demodulated usingthe first digital modulation scheme, and the PDU is demodulated usingthe second digital modulation scheme. The modulation rate of themodulation scheme for the PDU of the received audio data packet is lowerthan the data transmission rate, that is, a same symbol can carry morebits, thereby increasing an audio data transmission rate, and supportingtransmission of high-definition audio data.

In a possible design, the method further includes receiving a modulationscheme identifier of the BLE physical channel, and determining, based onthe modulation scheme identifier, that the physical layer frame headeruses the first digital modulation scheme, and determining, based on themodulation scheme identifier, that the PDU uses the second digitalmodulation scheme.

In the foregoing method, the first digital modulation scheme and thesecond digital modulation scheme can be determined based on themodulation scheme identifier, and then the audio data can besuccessfully demodulated.

In a possible design, the modulation rate of the first digitalmodulation scheme is equal to the data transmission rate, and the datatransmission rate is N times the modulation rate of the second digitalmodulation scheme, where N is an integer greater than 1.

In the foregoing method, high-definition audio data can be transmittedon the BLE physical channel at the data transmission rate based on thePDU that is modulated using the second digital modulation scheme.

In a possible design, after the obtaining audio data, the method furtherincludes returning an acknowledgement message to a sending device, wherethe acknowledgement message is used to indicate a receiving status ofthe audio data.

In the foregoing method, the acknowledgement message is returned to thesending device, to notify the sending device whether a receiving devicereceives the audio data.

According to a third aspect, an embodiment of this application providesan audio data transmission apparatus. The apparatus includes a basebandprocessor and a transmitter, the baseband processor encapsulates, basedon a physical layer frame header, a PDU including audio data, to obtainan audio data packet, where the physical layer frame header is modulatedusing a first digital modulation scheme, the PDU is modulated using asecond digital modulation scheme, a value of a modulation rate of thefirst digital modulation scheme is equal to a value of a datatransmission rate, and a value of a modulation rate of the seconddigital modulation scheme is less than the value of the datatransmission rate, and the transmitter sends the audio data packet on aBLE physical channel at the data transmission rate.

For the foregoing apparatus, the physical layer frame header ismodulated using the first digital modulation scheme, and the PDU ismodulated using the second digital modulation scheme. Because thephysical layer frame header and the PDU are modulated using twodifferent modulation schemes, the modulation rate of the modulationscheme for the PDU is lower than the data transmission rate, that is, asame symbol can carry more bits, thereby increasing an audio datatransmission rate. Therefore, transmission of high-definition audio datacan be supported.

In a possible design, the apparatus further includes an audio codecconfigured to generate a modulation scheme identifier of the BLEphysical channel, the baseband processor is configured to, based on themodulation scheme identifier, determine that the physical layer frameheader uses the first digital modulation scheme, and determine that thePDU uses the second digital modulation scheme, and the transmitter isconfigured to send the modulation scheme identifier.

In a possible design, the data transmission rate is N times themodulation rate of the second digital modulation scheme, where N is aninteger greater than 1.

In a possible design, the PDU includes a control layer frame header anda payload, the payload is used to carry the audio data, and the controllayer frame header includes indication information used to indicate alength of the audio data.

In a possible design, a bandwidth of the BLE physical channel is 2 MHz,or a bandwidth of the BLE physical channel is 4 MHz, and the physicalchannel having the bandwidth of 4 MHz is formed by combining twoadjacent physical channels each having a bandwidth of 2 MHz.

In a possible design, the first digital modulation scheme includes GFSK,and the second digital modulation scheme includes DQPSK or 8DPSK.

In a possible design, a modulation factor of the GFSK ranges from 0.45to 0.55.

In a possible design, the apparatus further includes an audio codec, thecodec is configured to query a codec parameter using the L2CAP, wherethe codec parameter includes a coding parameter of the audio data, andthe codec is further configured to encode original audio data based onthe coding parameter, to obtain the audio data.

According to a fourth aspect, an embodiment of this application providesan audio data transmission apparatus. The apparatus includes a receiverand a baseband processing module, the receiver is configured to receivean audio data packet on a BLE physical channel, where the audio datapacket includes a physical layer frame header and a PDU, and thebaseband processing module is configured to demodulate the physicallayer frame header using a first digital modulation scheme, anddemodulate the PDU using a second digital modulation scheme to obtainaudio data, where a value of a modulation rate of the first digitalmodulation scheme is equal to a value of a data transmission rate, and avalue of a modulation rate of the second digital modulation scheme isless than the value of the data transmission rate.

In the foregoing apparatus, the audio data packet is received on the BLEphysical channel, the physical layer frame header is demodulated usingthe first digital modulation scheme, and the PDU is demodulated usingthe second digital modulation scheme. The modulation rate of themodulation scheme for the PDU is lower than the data transmission rate,that is, a same symbol can carry more bits, thereby increasing an audiodata transmission rate, and supporting transmission of high-definitionaudio data.

In a possible design, the apparatus further includes an audio codec, thereceiver is configured to receive a modulation scheme identifier of theBLE physical channel, and the codec is configured to determine, based onthe modulation scheme identifier, that the physical layer frame headeruses the first digital modulation scheme, and determine, based on themodulation scheme identifier, that the PDU uses the second digitalmodulation scheme.

In a possible design, the value of the data transmission rate is N timesthe value of the modulation rate of the second digital modulationscheme, where N is an integer greater than 1.

According to a fifth aspect, an embodiment of this application providesan audio data transmission apparatus. The apparatus includes anencapsulation module and a transmission module, the encapsulation moduleencapsulates, based on a physical layer frame header, a PDU includingaudio data, to obtain an audio data packet, where the physical layerframe header is modulated using a first digital modulation scheme, thePDU is modulated using a second digital modulation scheme, a value of amodulation rate of the first digital modulation scheme is equal to avalue of a data transmission rate, and a value of a modulation rate ofthe second digital modulation scheme is less than the value of the datatransmission rate, and the transmission module sends the audio datapacket on a BLE physical channel at the data transmission rate.

In a possible design, the data transmission rate is N times themodulation rate of the second digital modulation scheme, where N is aninteger greater than 1.

In a possible design, the PDU includes a control layer frame header anda payload, the payload is used to carry the audio data, and the controllayer frame header includes indication information used to indicate alength of the audio data.

In a possible design, a bandwidth of the BLE physical channel is 2 MHz,or a bandwidth of the BLE physical channel is 4 MHz, and the physicalchannel having the bandwidth of 4 MHz is formed by combining twoadjacent physical channels each having a bandwidth of 2 MHz.

In a possible design, the first digital modulation scheme includes GFSK,and the second digital modulation scheme includes DQPSK or 8DPSK.

In a possible design, a modulation factor of the GFSK ranges from 0.45to 0.55.

In a possible design, the apparatus further includes a codec module, thecodec module is configured to query a codec parameter using the L2CAP,where the codec parameter includes a coding parameter of the audio data,and the codec module is further configured to encode original audio databased on the coding parameter, to obtain the audio data.

According to a sixth aspect, an embodiment of this application providesa high-speed audio data transmission apparatus. The apparatus includes areceiving module and a demodulation module, the receiving module isconfigured to receive an audio data packet on a BLE physical channel,where the audio data packet includes a physical layer frame header and aPDU, and the demodulation module is configured to demodulate thephysical layer frame header using a first digital modulation scheme, anddemodulate the PDU using a second digital modulation scheme to obtainaudio data, where a value of a modulation rate of the first digitalmodulation scheme is equal to a value of a data transmission rate, and avalue of a modulation rate of the second digital modulation scheme isless than the value of the data transmission rate.

In a possible design, the apparatus further includes a codec module, thereceiving module is configured to receive a modulation scheme identifierof the BLE physical channel, and the codec module is configured todetermine, based on the modulation scheme identifier, that the physicallayer frame header uses the first digital modulation scheme, anddetermine, based on the modulation scheme identifier, that the PDU usesthe second digital modulation scheme.

In a possible design, the value of the data transmission rate is N timesthe value of the modulation rate of the second digital modulationscheme, where N is an integer greater than 1.

According to a seventh aspect, an embodiment of this applicationprovides a computer-readable storage medium. The computer-readablestorage medium stores an instruction, and when the instruction runs on acomputer or a processor, the computer or the processor is enabled toperform the method according to any one of the first aspect or thesecond aspect or the possible designs thereof.

An eighth aspect of this application provides a computer program productincluding an instruction, where when the instruction runs on a computeror a processor, the computer or the processor is enabled to perform themethod according to any one of the first aspect or the second aspect orthe possible designs thereof.

DESCRIPTION OF DRAWINGS

FIG. 1 is an overall framework diagram of a typical BLUETOOTH systemaccording to an embodiment of this application.

FIG. 2 is an overall schematic structural diagram of a BLUETOOTH systemaccording to an embodiment of this application.

FIG. 3 is a schematic flowchart of audio data transmission in aBLUETOOTH system according to an embodiment of this application.

FIG. 4 is a schematic flowchart of querying an audio codec capabilityaccording to an embodiment of this application.

FIG. 5 is a schematic flowchart of configuring an audio codec accordingto an embodiment of this application.

FIG. 6 is a schematic flowchart of creating an audio connectionaccording to an embodiment of this application.

FIG. 7 is a schematic diagram of distribution of audio transmissionchannels according to an embodiment of this application.

FIG. 8 is a schematic structural diagram of a high-definition audiophysical frame according to an embodiment of this application.

FIG. 9 is a schematic diagram of a preamble format according to anembodiment of this application.

FIG. 10 is a schematic diagram of an audio PDU data format according toan embodiment of this application.

FIG. 11 is a schematic structural diagram of an audio PDU packet headeraccording to an embodiment of this application.

FIG. 12 is a schematic flowchart of ending an audio connection accordingto an embodiment of this application.

FIG. 13 is a schematic flowchart of an audio data transmission methodaccording to an embodiment of this application.

FIG. 14 is a schematic flowchart of an audio data transmission methodaccording to another embodiment of this application.

FIG. 15 is a schematic structural diagram of an audio data transmissiondevice according to an embodiment of this application.

FIG. 16 is a schematic structural diagram of an audio data transmissiondevice according to an embodiment of this application.

FIG. 17 is a structural diagram of an example hardware architecture of acomputing device that can implement an audio data transmission methodand device according to embodiments of this application.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is an overall framework diagram of a typical BLUETOOTH systemaccording to an embodiment of this application. As shown in the figure,the BLUETOOTH system includes a BLUETOOTH host and a BLUETOOTH module.The BLUETOOTH host exchanges data with the BLUETOOTH module through ahost controller interface (HCI) under control of an application programand a higher layer protocol. The BLUETOOTH host exchanges data withanother BLUETOOTH system using a host controller, a link manager(LinkManager), BLUETOOTH audio, baseband and link control, and radiofrequency in the BLUETOOTH module.

FIG. 2 is an overall schematic structural diagram of a BLUETOOTH systemaccording to an embodiment of this application. The BLUETOOTH systemincludes an audio source device 201, a BLUETOOTH controller 203, anaudio receiving device 202, and a BLUETOOTH controller 204. The audiosource device 201 sends audio data to the audio receiving device 202using the BLUETOOTH controller 203 and the BLUETOOTH controller 204.

A sending device includes the audio source device 201 and the BLUETOOTHcontroller 203. A receiving device includes the audio receiving device202 and the BLUETOOTH controller 204. In this embodiment of thisapplication, an example in which the sending device sends audio data tothe receiving device is used for description. It should be understoodthat the receiving device may also send audio data to the sending deviceusing a same technical solution.

In an optional case, a structure of the audio source device 201 is thesame as a structure of the audio receiving device 202. The structure ofthe audio source device is used as an example for description below. Theaudio source device 201 includes a BLUETOOTH host protocol stack module2011, an audio encoding module 2012, and a serial communication module2013.

When transmitting audio data, the BLUETOOTH host protocol stack module2011 may negotiate an audio encoding related parameter with the audioreceiving device 202 using the audio encoding module 2012. Further, theBLUETOOTH host protocol stack module 2011 may transmit the audio datausing the serial communication module 2013.

For example, the BLUETOOTH controller 203 includes a pulse-codemodulation (PCM) module 2014, a serial communication module 2015, an ACLand audio connection management module 2016, a BLUETOOTH baseband module2017, and a radio frequency module 2018.

The PCM module 2014 transmits an encoder parameter to the ACL and audioconnection management module 2016. The serial communication module 2015transmits the audio data to the ACL and audio connection managementmodule 2016. The ACL and audio connection management module 2016transmits data to the BLUETOOTH controller 204 using the BLUETOOTHbaseband module 2017 and the radio frequency module 2018.

For a structure and a function of the BLUETOOTH controller 204 of thereceiving device, refer to descriptions of the BLUETOOTH controller 203,and details are not described herein again.

An audio data transmission method provided in an embodiment of thisapplication is described below with reference to FIG. 2 and FIG. 3. Theaudio data transmission method further includes the following steps.

S1. Create an ACL connection.

For example, the audio source device creates an ACL connection to theaudio receiving device 202 using the BLUETOOTH host protocol stackmodule 2011. The ACL connection may be a conventional BLUETOOTH ACLconnection or a BLE ACL connection.

Further, the audio source device negotiates a codec parameter for theaudio source device and the audio receiving device using the L2CAP layerprotocol.

S2. The ACL connection is in a low energy state.

For example, when no audio is played or audio play is temporarilystopped, the ACL connection is in the low energy state with a short dutycycle.

In an example, when no audio is played or audio play is temporarilystopped, a breathing mode is used, where the breathing mode isimplemented by updating a connection parameter to set a long-intervalconnection mode. In the breathing mode, a quantity of slots for sendingdata by the sending device is reduced, and a quantity of slots listenedto by the receiving device is correspondingly reduced, to save power.

S3. The sending device creates an audio connection to the receivingdevice.

The sending device creates the audio connection to the receiving device,for transmission of high-definition audio data.

S4. Transmit audio data.

For example, the audio data is transmitted by the audio source device201 to the BLUETOOTH controller 203 through a HCI or an inter-integratedcircuit sound bus (I2S) interface after the audio source device 201performs compression coding (lossy or lossless) on audio PCM data at anapplication layer.

S5. Generate a PDU.

Referring to FIG. 2, after the serial communication module 2015 receivesthe audio data from the HCI interface, the serial communication module2015 transmits the audio data to the ACL and audio connection managementmodule 2016, or after the PCM module 2014 receives the audio data fromthe audio encoding module 2012, the PCM module 2014 transmits the audiodata to the ACL and audio connection management module 2016. The ACL andaudio connection management module 2016 encapsulates the audio data, togenerate the PDU.

For example, the PDU includes a control layer frame header and apayload. The payload is used to carry the audio data. It should beunderstood that the audio data carried in the payload may include audiodata obtained by encoding original audio data, and optionally, the audiodata may alternatively include audio data on which encryption andintegrity check are performed.

For example, FIG. 10 is a schematic diagram of a PDU data formataccording to an embodiment of this application. In an optional case, ifa payload is encrypted for transmission, message integrity check (MIC)is an integrity check bit of encrypted data, or if a payload is notencrypted for transmission, there is no MIC field.

For example, FIG. 11 is a schematic structural diagram of a PDU controllayer frame header according to an embodiment of this application. Theheader includes a next sequence number (NESN) field, a sequence number(SN) field, and a more data (MD) field that are used to performtransmission with a peer device. A transmission mechanism of a BLE ACLpacket is reused in this embodiment. A length of the NESN field is 1bit, a length of the SN field is 1 bit, a length of the MD field is 1bit, and a length of a reserved for future use (RFU) field is 2 bits.For example, the header includes indication information used to indicatea length of a payload. For example, in FIG. 11, the length indicationinformation is represented by Length, and optionally, a length of Lengthis 11 bits, and a valid value ranges from 0 to 2047.

S6. Encapsulate the PDU.

Referring to FIG. 2, the BLUETOOTH baseband module 2017 encapsulates thePDU based on a time sequence parameter negotiated by the ACL and audioconnection management module 2016. For example, the time sequenceparameter includes a maximum transmission length of the PDU, a minimumtransmission interval of the PDU, a maximum transmission interval of thePDU, and a connection anchor time of the PDU. The connection anchor timeof the PDU is a time point after a start point location of a currentlytransmitted message. For example, the PDU is encapsulated based on aphysical layer frame header, that is, one physical layer frame header isadded before the PDU. In an optional case, the physical layer frameheader is modulated using a GFSK modulation scheme having a modulationfactor ranging from 0.45 to 0.55. The physical layer frame header mayuse a 2 MHz/4 MHz frame header of the GFSK. For example, theencapsulated PDU may be referred to as an audio data packet. FIG. 8 is aschematic structural diagram of a physical frame of an audio data packetaccording to an embodiment of this application.

Some fields in the physical frame are described below.

(1) Preamble

FIG. 9 is a schematic diagram of a preamble format according to anembodiment of this application.

A time of the preamble is always 8 microseconds. A preamble of ahigh-definition 2 MHz channel includes 16 bits, and a preamble of ahigh-definition 4 MHz channel includes 32 bits. A bit format “1010” or“0101” is determined based on the first bit “1” or “0” of an accessaddress.

In an example, if the first bit of the access address is 1, the preamblestarts with “1010”, or if the first bit of the access address is 0, thepreamble starts with “0101”.

(2) Referring to FIG. 9, the access address includes 32 bits, and aformat in the BLUETOOTH BLE protocol is reused.

(3) Referring to FIG. 8, a trailer of the GFSK includes 12 all-zerobits.

(4) Referring to FIG. 8, a guard time is an interval calculated from thelast trailer bit of the GFSK to the first bit of a DPSK synchronizationword (sync word).

In an example, the guard time may be 5 microseconds, however,considering an actual fluctuation, the guard time is allowed to changewithin +/−0.25 microsecond. Values of the guard time may all be 0, ormay be in a repeated form such as 0101.

(5) Referring to FIG. 8, a sync word of a DQPSK modulation scheme is 11symbols and follows an EDR DQPSK design in a BLUETOOTH protocol. Thefirst symbol is any phase (reference), and bits of the last 10 symbolsare 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, −1, 1, 1, 1, 0, 1, 0, 1, and

A sync word of an 8DPSK modulation scheme is 11 symbols and follows anEDR 8DPSK design in a BLUETOOTH protocol. The first symbol is areference, and bits of the last 10 symbols are 0, 1, 0, 1, 1, 1, 0, 1,0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, and 0.

(6) Referring to FIG. 8, a cyclic redundancy check (CRC) design followsa CRC structure of a BLE PDU, that is, a CRC includes a total of 24bits. A linear-feedback shift register (LFSR) function isX24+X10+X9+X6+X4+X3+X+1.

(7) Referring to FIG. 8, a trailer of the DPSK is all-zero bits of twosymbols.

A trailer bit of a DQPSK modulation scheme is {00, 00}, and a trailerbit of an 8DPSK modulation scheme is {000, 000}.

S7. Send the encapsulated PDU.

The radio frequency module 2018 sends, to a radio frequency module 2028,the PDU including the audio data.

S8. The BLUETOOTH controller 204 receives data.

The radio frequency module 2028 receives data from an air interface, andthen transmits the data to a BLUETOOTH baseband module 2027 fordemodulation, and then transmits the data to an ACL and audio connectionmanagement module 2026.

The ACL and audio connection management module 2026 is responsible forextracting the audio data and buffering the audio data, and transmittingthe audio data to a serial communication module 2025 or a PCM module2024.

S9. The audio receiving device 202 receives the audio data.

The serial communication module 2025 or the PCM module 2024 transmitsthe audio data to an audio codec module 2022 or a serial communicationmodule 2023.

S10. A BLUETOOTH host protocol stack module 2021 receives the audiodata.

The audio codec module 2022 or the serial communication module 2023transmits the audio data to the BLUETOOTH host protocol stack module2021.

S11. Play the audio data.

The BLUETOOTH host protocol stack module 2021 decodes the audio data andtransmits the audio data to an audio application. The audio applicationcan play the audio data through an audio interface of the audioreceiving device 202.

In an optional case, the audio receiving device 202 returns anacknowledgement message to the audio source device 201, where theacknowledgement message is used to indicate a receiving status of theaudio data. In an example, the acknowledgement message may be a BLEempty packet. Because the empty packet uses the GFSK modulation scheme,an anti-interference capability is strong, thereby facilitatingreceiving by the audio source device 201.

For example, FIG. 4 is a schematic flowchart of negotiating an audiocodec parameter according to an embodiment of this application. Thenegotiation may further include the following steps.

401. An audio source device sends a GET_AUDIO_CODEC_CAPACITY_REQmessage.

After an ACL connection is established between a sending device and areceiving device, the sending device may query an audio codec parameterof the receiving device, and correspondingly, the receiving device mayalso query a codec parameter of the sending device.

FIG. 4 is a schematic flowchart of querying an audio codec capabilityaccording to an embodiment of this application. An audio codeccapability is queried based on a L2CAP channel.

Before the sending device transmits audio data to the receiving device,an audio source device 201 queries a codec parameter using a BLUETOOTHcontroller of a sending device 203, a BLUETOOTH controller 204 of thereceiving device, and an audio receiving device 202.

First, the audio source device 201 sends theGET_AUDIO_CODEC_CAPACITY_REQ message using the BLUETOOTH controller 203of the sending device, the BLUETOOTH controller 204 of the receivingdevice, and the audio receiving device 202, to learn of a codec index.The codec index includes an identifier of the codec parameter. In anexample, the codec index includes a codec 0 and a codec 1.

Table 1 shows an example format of the GET_AUDIO_CODEC_CAPACITY_REQmessage provided in this embodiment of this application.

TABLE 1 7    6  5    4   3   2    1    0 Byte Session identifier:session ID 0 Command identifier: GET_AUDIO_CODEC_CAPACITY_REQ 1 Codecindex: codec index 2

In Table 1, a valid range of the session identifier may be 1 to 128.

The command identifier of the message is GET_AUDIO_CODEC_CAPACITY_REQ,and has a value of 1.

The codec index starts from 0. For example, when the codec index is0xff, all codec capabilities are returned.

402. The audio receiving device 202 sends GET_AUDIO_CODEC_CAPACITY_RSP.

Then the audio receiving device 202 sends theGET_AUDIO_CODEC_CAPACITY_RSP using the BLUETOOTH controller 204 of thereceiving device, the BLUETOOTH controller 203 of the sending device,and the audio source device 201, to respond to codec capability queryrequest information such that the audio source device 201 learns of acodec parameter. In an example, the codec index includes a codec 0 and acodec 1, and the GET_AUDIO_CODEC_CAPACITY_RSP message includes a codecparameter with 0 and a codec parameter with 1.

Table 2 shows an example format of the GET_AUDIO_CODEC_CAPACITY_RSPprovided in this embodiment of this application.

TABLE 2 7  6   5    4      3   2  1    0 Byte Session identifier:session ID 0 Command identifier: GET_AUDIO_CODEC_CAPACITY_RSP 1 Codecparameter: codec parameter with 0 Codec parameter: codec parameter with1 . . .

In Table 2, a valid range of the session identifier may be 1 to 128.

The command identifier is GET_AUDIO_CODEC_CAPACITY_RSP, and has a valueof 2.

Table 3 shows an example of a data structure of a codec parameterprovided in this embodiment of this application.

TABLE 3 Parameter Byte name Meaning quantity Codec index The codec indexstarts from 0. If the 1 codec index is 0xff, it indicates that there isno codec parameter. Encoding Subband code (subband code, SBC), 1 typemoving picture experts group (MPEG), MPEC-1, MPEG-2, and adaptivetransform acoustic coding (Adaptive Transform Acoustic Coding, ATRAC)Transmission 0: A2DP profile 1 mode 1: Transmission method in thisembodiment of this application Supported Bit 0: When this bit is set to1, it 1 sampling indicates supporting 16000 samples/16 bits. rate Bit 1:When this bit is set to 1, it indicates supporting 32000 samples/16bits. Bit 2: When this bit is set to 1, it indicates supporting 48000samples/16 bits. Bit 3: When this bit is set to 1, it indicatessupporting 96000 samples/16 bits. Bit 4: When this bit is set to 1, itindicates supporting 48000 samples/24 bits. Bit 5: When this bit is setto 1, it indicates supporting 96000 samples/24 bits. Another bit:reserved for extension Audio 0: Mono 1 channel 1: Binaural mode 2:Stereo Another value reserved

It should be understood that the message formats shown in Table 1 toTable 3 are merely examples for description in the embodiments of thisapplication, and are not intended to limit a message format. The valuesand the ranges of the parameters provided in the tables are alsooptional. Neither a message format nor a parameter value is limited inthis application.

For example, based on the obtained codec capability, the audio sourcedevice configures specific codec parameters, for example, a negotiatedencoding type for transmitting audio data between the audio sourcedevice and the audio receiving device, a transmission mode, a samplingrate, and an audio channel, to ensure that the audio source device andthe audio receiving device use consistent codec parameters.

FIG. 5 is a schematic flowchart of configuring an audio codec accordingto an embodiment of this application. The audio codec configurationprocedure further includes the following steps.

501. An audio source device 201 sends an AUDIO_CONFIG_CODEC_REQ message.

First, the audio source device 201 sends the AUDIO_CONFIG_CODEC_REQmessage using a BLUETOOTH controller 203 of a sending device, aBLUETOOTH controller 204 of a receiving device, and an audio receivingdevice 202, to select a codec parameter based on a codec index. In anexample, if the codec index includes a codec 0 and a codec 1, a codecparameter with 0 and a codec parameter with 1 may be returned in theGET_AUDIO_CODEC_CAPACITY_RSP message.

Table 4 shows an example format of the AUDIO_CONFIG_CODEC_REQ messageprovided in this embodiment of this application.

TABLE 4 7    6  5   4   3   2   1   0   Byte Session identifier: sessionID 0 Command identifier: AUDIO_CONFIG_CODEC_REQ 1 Codec index: codecindex 2

In Table 4, the session identifier starts from 1, and is used todistinguish between different requests.

The command identifier is AUDIO_CONFIG_CODEC_REQ, and has a value of 3.

A valid value of the codec index starts from 0. For example, the codecindex may be selected from a codec list returned in theGET_AUDIO_CODEC_CAPACITY_RSP message shown in Table 2.

502. The audio receiving device 202 sends an AUDIO_CONFIG_CODEC_CFMmessage.

Then the audio receiving device 202 sends the AUDIO_CONFIG_CODEC_CFMmessage to the audio source device 201 using the BLUETOOTH controller204 of the receiving device and the BLUETOOTH controller 203 of thesending device, to notify the audio source device 201 of a configurationstatus of a codec parameter. In an example, if the configuration statusis 0, it indicates that the codec parameter is successfully configured,or if the configuration status is not 0, it indicates that the codecparameter is unsuccessfully configured.

Table 5 shows an example format of the AUDIO_CONFIG_CODEC_CFM messageprovided in this embodiment of this application.

TABLE 5 7     6  5   4    3   2   1   0  Byte Session identifier:session ID 0 Command identifier: AUDIO_CONFIG_CODEC_CFM 1 Configurationstatus 2

In Table 5, the session identifier starts from 1, and corresponds to asession identifier of the received AUDIO_CONFIG_CODEC_REQ message.

The command identifier is AUDIO_CONFIG_CODEC_CFM, and has a value of 4.

For the configuration status, 0 indicates a success, and another valueindicates an error.

For example, for ease of understanding of a process of creating an audioconnection, namely, S3, FIG. 6 is a signaling flowchart of a method forcreating an audio connection according to an embodiment of thisapplication. The method includes the following steps.

601. An audio source device 201 sends a Setup audio stream command to aBLUETOOTH controller 203.

It should be understood that, before the audio source device sends datato an audio receiving device, an audio connection needs to be created.In this embodiment of this application, a data transmission rate of aphysical channel for transmitting an audio stream includes 4 Mb/s, 6Mb/s, 8 Mb/s, or 12 Mb/s. Therefore, in a process of creating an audioconnection, a physical channel for transmitting an audio stream needs tobe determined.

For example, the audio source device 201 sends the Setup audio streamcommand to the BLUETOOTH controller 203, to notify the audio receivingdevice of a physical channel on which the audio stream is transmitted.In an example, 0 indicates a physical channel at a rate of 4 Mb/s, 1indicates a physical channel at a rate of 6 Mb/s, 2 indicates a physicalchannel at a rate of 8 Mb/s, and 3 indicates a physical channel at arate of 12 Mb/s. The physical channel for transmitting the audio streamcan be learned of using a number.

For example, Table 6 shows a format of the Setup audio stream commandprovided in this embodiment of this application. Phy type may be used toidentify the physical channel for transmitting the audio stream.

TABLE 6 Command parameter Description Value range ACL handle ACLconnection Consistent with a range of an handle related to a ACLconnection handle in a high-definition audio BT specification stream Maxpayload A maximum audio 0 to 2047 bytes size payload size, calculated inbytes Phy type Physical channel for 0 indicates a physical channeltransmitting an audio at a rate of 4 Mb/s, stream 1 indicates a physicalchannel at a rate of 6 Mb/s, 2 indicates a physical channel at a rate of8 Mb/s, and 3 indicates a physical channel at a rate of 12 Mb/s.

602. The BLUETOOTH controller 203 sends a Setup audio command CompleteEvent message to the audio source device 201.

For example, the BLUETOOTH controller 203 notifies, based on the Setupaudio command Complete Event message, the audio source device 201 of aresult of executing the Setup audio stream command. Optionally, theBLUETOOTH controller 203 allocates an audio connection identifier to acurrent audio stream using the Setup audio command Complete Eventmessage.

For example, Table 7 shows a format of the Setup audio command CompleteEvent message provided in this embodiment of this application.

TABLE 7 Event parameter Description Value range Status Command execution0: successful command status execution 1: invalid command parameterAudio connect Connection identifier pre- 0 to 256 handle allocated tothe audio connection

In an optional case, when a “status” of the Setup audio command CompleteEvent message returned by the BLUETOOTH controller to the audio sourcedevice is 0, it indicates that an audio stream setup command issuccessfully executed, or optionally, when a “status” is 1, it indicatesthat an audio stream setup command parameter is invalid.

603. The audio source device 201 sends an Enable audio stream command tothe BLUETOOTH controller 203.

For example, the Enable audio stream command is used to enable ordisable an audio stream command, that is, whether the audio sourcedevice agrees or disagrees to transmit the current audio stream using anaudio connection identifier that is allocated using a Setup audiocommand Complete Event.

For example, Table 8 shows an example format of the Enable audio streamcommand provided in this embodiment of this application.

TABLE 8 Command parameter Description Value range Audio connection Audioconnection 0 to 256 handle identifier Enable 0: Disable 0 or 1 1: Enable

For example, when “enable” in the Enable audio stream command is 0, itindicates that the audio source device disagrees to transmit the currentaudio stream using the allocated audio connection identifier, oroptionally, when “enable” in the Enable audio stream command is 1, itindicates that the audio source device agrees to transmit the currentaudio stream using the allocated audio connection identifier.

604. The BLUETOOTH controller 203 sends an Enable audio stream commandStatus message to the audio source device 201.

The Enable audio stream command Status message is used to return astatus after the Enable audio stream command is executed, that is,notify the audio source device of whether the Enable audio streamcommand is successfully executed.

For the Enable audio stream command Status message, for example, Table 9shows a format of the Enable audio stream command Status messageprovided in this embodiment of this application.

TABLE 9 Command parameter Description Value range Status Command 0:successful command execution status 1: invalid command parameter Anothervalue

605. The BLUETOOTH controller 203 sends an AUDIO_CONNECTION_REQ messageto the BLUETOOTH controller 204, to request to set up an audioconnection between the sending device and the receiving device.

For example, Table 10 shows a format of the AUDIO_CONNECTION_REQ messageprovided in this embodiment of this application.

TABLE 10 Message parameter Description Value range Audio connectionAudio 0 to 256 handle identifier connection Audio Phy type Type of aphysical 0 indicates a physical channel channel for audio at a rate of 4Mb/s, transmission 1 indicates a physical channel at a rate of 6 Mb/s, 2indicates a physical channel at a rate of 8 Mb/s, and 3 indicates aphysical channel at a rate of 12 Mb/s. Max payload size Maximum 0 to2047 bytes transmission length Min connection Minimum connection 0 to65535 microseconds interval interval Max connection Maximum connection 0to 65535 microseconds interval interval Anchor point Connection anchor 1to 65535, at a step of time: a time point 625 microseconds after a startpoint location of a currently transmitted message

606. The BLUETOOTH controller 204 sends an Audio stream req eventmessage to the audio receiving device 202, to notify the audio receivingdevice 202 that there is an audio connection request.

For example, Table 11 shows a format of the Audio stream req eventmessage provided in this embodiment of this application.

TABLE 11 Message parameter Description Value range ACL connection ACL 0to 0xfffe handle connection identifier Audio connection Audio 0 to 256handle connection identifier Audio Phy type Type of a physical 0indicates a physical channel channel for audio at a rate of 4 Mb/s,transmission 1 indicates a physical channel at a rate of 6 Mb/s, 2indicates a physical channel at a rate of 8 Mb/s, and 3 indicates aphysical channel at a rate of 12 Mb/s. Max payload size Maximum 0 to2047 bytes transmission length Min connection Minimum connection 0 to65535 microseconds interval interval Max connection Maximum connection 0to 65535 microseconds interval interval

607. The audio receiving device 202 sends an Audio stream accept commandmessage to the BLUETOOTH controller 204 such that the audio receivingdevice 202 instructs the BLUETOOTH controller 204 to accept the audioconnection request.

For example, Table 12 shows a format of the Audio stream accept commandmessage provided in this embodiment of this application.

TABLE 12 Message parameter Description Value range Audio connectionAudio connection 0 to 256 handle identifier

For example, the Audio stream accept command message carries an audioconnection identifier. Optionally, the audio connection identifier maybe any integer ranging from 0 to 256, and an audio connection on which acurrent audio data stream is transmitted is determined using the audioconnection identifier.

608. The BLUETOOTH controller 204 sends an AUDIO_CONNECTION_RSP messageto the BLUETOOTH controller 203. For example, the AUDIO_CONNECTION_RSPmessage may be an ACL control PDU message, and is used to return amessage status to the BLUETOOTH controller 203 using a parameter. In anexample, when the parameter is 0, the returned message status is“accepting the AUDIO_CONNECTION_REQ message”, or when the parameter is1, the returned message status is “invalid parameter”, or when theparameter is 2, the returned message status is “system busy”, or whenthe parameter is 3, the returned message status is “insufficientresources”.

For example, Table 13 shows a format of the AUDIO_CONNECTION_RSP messageprovided in this embodiment of this application.

TABLE 13 Message parameter Description Value range Status Message status0: accepting the reply AUDIO_CONNECTION_ notification REQ message 1:invalid parameter 2: system busy 3: insufficient resources Audio Audio 0to 256 connection connection handle identifier Preferred Acceptableclock 0 to 65535 microseconds offset offset relative to an anchor point

609. The BLUETOOTH controller 203 sends an AUDIO_CONNECTION_CONFIRMmessage to the BLUETOOTH controller 204, to indicate that the audioconnection request can be accepted.

For example, Table 14 shows a format of the AUDIO_CONNECTION_CONFIRMmessage provided in this embodiment of this application.

TABLE 14 Message parameter Description Value range Audio connectionAudio connection 0 to 256 handle identifier Access address Value of anaccess 32 bits, a generated address of the audio format needs to meetconnection a requirement for a BLUETOOTH access address. CRC init valueCRC initial value of the 0x00 to 0xffff audio connection Anchor pointConnection anchor time: 1 to 65535, at a step a time point after a startof 625 microseconds point location of a currently transmitted messageOffset Offset relative to an 0 to 65535 anchor point, used tomicroseconds precisely set a sending time point of the audio dataChannel map Corresponding to 1 to 40 corresponding available channelmapping, a channel index is from 0 to 39, and is mapped to 40 bits, forexample, a zeroth bit corresponds to a channel 0, a first bitcorresponds to a channel 1, and the rest may be deduced by analogy. If avalue of a bit is 0, it indicates that the channel is unavailable, or ifa value of a bit is 1, it indicates that the channel is available.Hopstep Frequency hopping step 1 to 16

610. The BLUETOOTH controller 203 sends an Audio connection ready eventmessage to the audio receiving device 202.

The BLUETOOTH controller 203 notifies, based on the Audio connectionready event message, the audio source device 201 that the audioconnection is already established, or the BLUETOOTH controller 204 maynotify, based on the Audio connection ready event message, the audioreceiving device 202 that the audio connection is already established,and then the audio data can be transmitted between the audio sourcedevice 201 and the audio receiving device 202.

For example, Table 15 shows a message structure of the Audio connectionready event provided in this embodiment of this application.

TABLE 15 Event parameter Description Value range Status Command 0:successful audio execution status connection 1: unsuccessful audioconnection Audio Connection identifier pre- 0 to 256 connect allocatedto the audio handle connection

611. The audio source device 201 sends audio stream data to theBLUETOOTH controller 203.

The audio data is transmitted by the audio source device 201 to theBLUETOOTH controller 203 through a HCI or an I2S interface after theaudio source device 201 performs compression coding (lossy or lossless)on audio PCM data at an application layer.

612. The BLUETOOTH controller 203 sends LL_AUDIO_DATA to the BLUETOOTHcontroller 204.

The BLUETOOTH controller 203 sends, to the BLUETOOTH controller 204, aPDU including the audio data.

Modulation of the audio data is described below with reference to FIG.7.

FIG. 7 is a schematic diagram of distribution of audio transmissionchannels according to an embodiment of this application.

A BLUETOOTH basic rate (BR) and an EDR mode are based on a bandwidth of1 MHz, channel center frequencies are 2402 MHz, 2403 MHz, 2404 MHz, . .. , 2479 MHz, and 2480 MHz, and there are a total of 79 channels.

BLE is based on a bandwidth of 2 MHz, channel center frequencies are2402 MHz, 2404 MHz, 2406 MHz, . . . , 2478 MHz, and 2480 MHz, and thereare a total of 40 channels.

In this embodiment of this application, there are two bandwidths forhigh-definition audio transmission 2 MHz and 4 MHz. For coexistence ofBLUETOOTH channels and to reduce interference between existing BLUETOOTHchannels, in a high-definition 2 MHz mode, same BLE 2 MHz physicalchannels are distributed, while in a high-definition 4 MHz mode, BLE 2MHz physical channels are aggregated to combine two adjacent 2 MHzphysical channels into a 4 MHz physical channel, where a centerfrequency of the 4 MHz physical channel is equal to an average value ofcenter frequencies of the two adjacent 2 MHz physical channels. Thereare a total of 20 channels for the high-definition 4 MHz mode, and thisconforms to an access requirement for at least 20 channels for afrequency hopping system in many countries.

In an optional case, voice transmission in a BLUETOOTH protocol isperformed in the EDR mode, a frame header is modulated using a GFSKscheme having a modulation factor of 0.32, a payload is modulated usingDQPSK or 8DPSK, and a symbol rate is 1 MHz. A bit rate of the DQPSK istwice the symbol rate, namely, 2 Mb/s, and a bit rate of the 8DPSK isthree times the symbol rate, namely, 3 Mb/s. It should be understoodthat, in this embodiment of this application, the symbol rate may alsobe referred to as a modulation rate, or the bit rate may also bereferred to as a data transmission rate.

A feature of EDR is to increase a data transmission rate of a BLUETOOTHtechnology to 2.1 Mb/s. In addition to achieving more stable audiostream transmission and lower power consumption, an advantage of abandwidth can be fully used to connect a plurality of BLUETOOTH devices.

BLE is a low-cost, short-range, interoperable, and robust wirelesstechnology. The BLE uses many intelligent means to minimize powerconsumption. Specifically, a variable connection time interval may beused, and the interval may be set to several milliseconds to severalseconds based on a specific application. In addition, because the BLEuses a very fast connection method, a power-saving state can bemaintained usually. In this case, two ends of a link only know that apeer end is still connected. The link is enabled only when necessary,and then the link is disabled in a shortest possible time.

In this embodiment of this application, the PDU including the audio datamay be encapsulated based on a physical layer frame header, to obtain anaudio data packet. The physical layer frame header is modulated using afirst digital modulation scheme, and the PDU is modulated using a seconddigital modulation scheme. A value of a modulation rate of the firstdigital modulation scheme is equal to a value of a data transmissionrate, and a value of a modulation rate of the second digital modulationscheme is less than the value of the data transmission rate. In thisway, the audio data packet can be sent at the data transmission rate ona BLE physical channel. It should be understood that a modulation rateof a modulation scheme is a symbol rate in a unit of hertz (Hz), a datatransmission rate is a bit rate in a unit of bits per second (bps), andthere is usually a proportional relationship between a value of themodulation rate of the modulation scheme and a value of the datatransmission rate. For example, one symbol in the GFSK modulation schemecarries one information bit, and therefore, a modulation rate (symbolrate) of the GFSK modulation scheme is equal to the data transmissionrate (bit rate), one symbol in the DQPSK modulation scheme carries twoinformation bits, and therefore, a modulation rate (symbol rate) of a2*DQPSK modulation scheme is equal to the data transmission rate (bitrate), and one symbol in the 8DPSK modulation scheme carries threeinformation bits, and therefore, a modulation rate (symbol rate) of a3*DQPSK modulation scheme is equal to the data transmission rate (bitrate). It should be understood that, because the unit of the modulationrate is different from that of the data transmission rate, the foregoingproportional relationship indicates a proportion between the values,regardless of the unit.

There are three modulation methods for a digital signal amplitudemodulation, frequency modulation, and phase modulation. Other variousmodulation methods are improved combinations of the three methods.Gaussian minimum shift keying (GMSK) is an improvement of minimum shiftkeying (MSK), and is to insert a Gaussian low-pass pre-modulation filterbefore an MSK modulator to increase spectrum utilization and improvecommunication quality.

In an example, the modulation scheme for the frame header may be theGFSK. In addition, when the modulation factor of the GFSK is equal to amodulation factor of GFSK in the BLE, an original hardware device can beused, without a need to update a device, thereby saving hardwareresources. The modulation factor of the GFSK in the BLE ranges from 0.45to 0.55, that is, the modulation factor of the GFSK in the BLE isgreater than or equal to 0.45, and less than or equal to 0.55.

In this embodiment of this application, the audio data may betransmitted based on the EDR mode. For combination with a BLUETOOTH BLEmode, the modulation factor of the GFSK of the physical layer frameheader is equal to the modulation factor of the GFSK in the BLE. Thatis, the physical layer frame header uses the GFSK scheme having amodulation factor ranging from 0.45 to 0.55, and the payload uses theDQPSK or the 8DPSK.

In this embodiment of this application, the modulation scheme for thephysical layer frame header is referred to as the first digitalmodulation scheme, and the modulation scheme for the payload is referredto as the second digital modulation scheme. A relationship between thefirst digital modulation scheme and the second digital modulation schemeand the data transmission rate may be the value of the modulation rateof the first digital modulation scheme is equal to the value of the datatransmission rate, and the value of the modulation rate of the seconddigital modulation scheme is less than the value of the datatransmission rate.

The physical layer frame header is modulated using the first digitalmodulation scheme, and the PDU is modulated using the second digitalmodulation scheme. Because the physical layer frame header and the PDUare modulated using two different modulation schemes, the modulationrate of the physical layer frame header is different from the modulationrate of the PDU, and the modulation rate of the modulation scheme forthe PDU is lower than the data transmission rate, that is, a same symbolcan carry more bits, thereby increasing an audio data transmission rate.Therefore, transmission of high-definition audio data can be supported.

In an example, the data transmission rate is N times the modulation rateof the second digital modulation scheme, where N is an integer greaterthan 1.

In this embodiment of this application, the modulation scheme that canbe used by the physical layer frame header is the GFSK, and themodulation scheme that can be used by the payload is the DQPSK or the8DPSK.

For the GFSK modulation scheme, the data transmission rate is equal tothe modulation rate of the GFSK.

For the DQPSK modulation scheme, the data transmission rate is twice themodulation rate of the DQPSK.

For the 8DPSK modulation scheme, the data transmission rate is threetimes the modulation rate of the 8DPSK.

In this embodiment of this application, a modulation rate of ahigh-definition 2 MHz mode is 2 MHz, a data transmission rate of GFSK inthe high-definition 2 MHz mode is 2 MHz, a data transmission rate ofDQPSK in the high-definition 2 MHz mode is twice the modulation rate,namely, 4 Mb/s, and a data transmission rate of 8DPSK is three times themodulation rate, namely, 6 Mb/s.

A modulation rate of a high-definition 4 MHz mode is 4 MHz, a datatransmission rate of GFSK in the high-definition 4 MHz mode is 4 MHz, adata transmission rate of DQPSK in the high-definition 4 MHz mode istwice the modulation rate, namely, 8 Mb/s, and a data transmission rateof 8DPSK is three times the modulation rate, namely, 12 Mb/s.

It can be learned from the foregoing content that, in thehigh-definition 2 MHz mode, a highest data transmission rate is 6 Mb/s,and in the high-definition 4 MHz mode, a highest data transmission rateis 12 Mb/s.

Apparently, based on the technical solution in this embodiment of thisapplication, the value of the data transmission rate is greater than 3Mb/s. In this way, transmission of high-definition audio data can besupported.

Table 16 shows a correspondence between a BLUETOOTH voice and a bitrate. It can be learned from content in Table 16 that, in thisembodiment of this application, the audio data can be transmitted on aphysical channel having a bandwidth of 2 MHz or a bandwidth of 4 MHzbased on the EDR mode. The frame header may be modulated using the GFSKhaving a modulation factor that is equal to a BLE modulation factor. Thepayload is modulated using the DQPSK or the 8DPSK. In this way, theaudio data can be transmitted in the EDR mode on the BLE channel.

TABLE 16 Modulation Modulation scheme for scheme Symbol thef rame forthe rate header payload Bit rate BLUETOOTH 1 MHz GFSK (0.32) DQPSK 2Mb/s voice 8DPSK 3 Mb/s High- 2 MHz GFSK (0.45 DQPSK 4 Mb/s definitionto 0.55) 8DPSK 6 Mb/s voice 2 MHz mode High- 4 MHz GFSK (0.45 DQPSK 8Mb/s definition to 0.55) 8DPSK 12 Mb/s  voice 4 MHz mode

After receiving the acknowledgement message, the audio source device mayend the audio connection. The audio data is transmitted to the audioreceiving device 202 using the audio source device 201, the BLUETOOTHcontroller 203, and the BLUETOOTH controller 204.

FIG. 12 is a schematic flowchart of ending an audio connection accordingto an embodiment of this application.

1201. An audio source device 201 sends an Enable audio stream command toa BLUETOOTH controller 203.

The audio source device 201 sends the Enable audio stream command to theBLUETOOTH controller 203, to apply to the BLUETOOTH controller 203 forending an audio connection.

For example, for a message format of the Enable audio stream commandprovided in this embodiment of this application, refer to Table 17,where an enable parameter is 0, and 0 indicates ending an audioconnection.

TABLE 17 Command Value parameter Description range Audio connect handleAudio connection identifier 0 to 256 Enable 0: Ending an audioconnection 0

1202. The BLUETOOTH controller 203 sends an Enable audio stream commandStatus message to the audio source device 201.

The BLUETOOTH controller 203 sends the Enable audio stream commandStatus message to the audio source device 201, to return, to the audiosource device 201, a status after the Enable audio stream command isexecuted.

For example, for a message format of the Enable audio stream commandStatus message provided in this embodiment of this application, refer toTable 9.

1203. The BLUETOOTH controller 203 sends an AUDIO_DISCONNECT_REQ messageto a BLUETOOTH controller 204.

The BLUETOOTH controller 203 sends the AUDIO_DISCONNECT_REQ message tothe BLUETOOTH controller 204, to determine that an identifier for endingthe audio connection is required.

For example, for a format of the AUDIO_DISCONNECT_REQ message providedin this embodiment of this application, refer to Table 18.

TABLE 18 Value Message parameter Description range Audio connectionhandle Audio connection identifier 0 to 256 Reason Reason for ending theaudio 0 to 256 connection

1204. The BLUETOOTH controller 204 sends an AUDIO_DISCONNECT_CFM messageto the BLUETOOTH controller 203.

The BLUETOOTH controller 204 sends the AUDIO_DISCONNECT_CFM message tothe BLUETOOTH controller 203, to determine that the identifier forending the audio connection is required.

For example, for a format of the AUDIO DISCONNECT CFM message providedin this embodiment of this application, refer to Table 19.

TABLE 19 Message parameter Description Value range Audio connectionAudio connection 0 to 256 handle identifier Status Audio 0: successfuldisconnection disconnection Another value: unsuccessful statusdisconnection

1205. The BLUETOOTH controller 203 sends an Audio stream disconnectedevent to the audio receiving device 202 using the audio source device201 and the BLUETOOTH controller 204.

The BLUETOOTH controller 203 sends the Audio stream disconnected eventto the audio source device 201, and the BLUETOOTH controller 204 sendsthe Audio stream disconnected event to the audio receiving device 202,to notify whether the audio connection is successfully ended.

For example, for a format of the Audio stream disconnected eventprovided in this embodiment of this application, refer to Table 20.

TABLE 20 Message parameter Description Value range Audio connectionAudio connection 0 to 256 handle identifier Status Audio 0: successfuldisconnection disconnection Another value: unsuccessful statusdisconnection

So far, in this embodiment of this application, an audio codec parameteris first negotiated, and then the audio codec parameter is configured.After the audio connection is created, the audio source device 201transmits audio with the audio receiving device 202 using the BLUETOOTHcontroller 204 and the BLUETOOTH controller 203. Finally, the audioconnection is ended.

FIG. 13 is a schematic flowchart of an audio data transmission methodaccording to an embodiment of this application. This embodiment of thisapplication is performed by a sending device. The audio datatransmission method further includes the following steps.

S1301. Encapsulate, based on a physical layer frame header, a PDUincluding audio data, to obtain an audio data packet, where the physicallayer frame header is modulated using a first digital modulation scheme,the PDU is modulated using a second digital modulation scheme, a valueof a modulation rate of the first digital modulation scheme is equal toa value of a data transmission rate, and a value of a modulation rate ofthe second digital modulation scheme is less than the value of the datatransmission rate.

The sending device needs to send the audio data to a receiving device.The sending device modulates the frame header based on the first digitalmodulation scheme. In an example, a modulation scheme for a data signalmay be GFSK.

For combination with a BLE mode, the frame header may use a GFSK schemehaving a modulation factor ranging from 0.45 to 0.55. The PDU is used tocarry the audio data, and the PDU is modulated using the second digitalmodulation scheme. In an example, the PDU may be modulated using DQPSKor 8DPSK.

S1302. Send the audio data packet on a BLE physical channel at the datatransmission rate.

The sending device can send the audio data packet on the BLE physicalchannel. In this way, the receiving device can receive the encapsulatedPDU on the BLE physical channel.

In this embodiment of this application, the physical layer frame headeris modulated using the first digital modulation scheme, and the PDU ismodulated using the second digital modulation scheme. Because thephysical layer frame header and the PDU are modulated using twodifferent modulation schemes, the modulation rate of the modulationscheme for the PDU is lower than the data transmission rate, that is, asame symbol can carry more bits, thereby increasing an audio datatransmission rate. Therefore, transmission of high-definition audio datacan be supported.

In an embodiment of this application, a codec generates a modulationscheme identifier of the BLE physical channel such that based on themodulation scheme identifier, it can be determined that the physicallayer frame header uses the first digital modulation scheme and the PDUuses the second digital modulation scheme, and sends the modulationscheme identifier. The modulation scheme used by the physical layerframe header and the modulation scheme used by the PDU can be determinedbased on the modulation scheme identifier. In this way, the sendingdevice can modulate the physical layer frame header and the PDU usingthe determined modulation schemes.

In an embodiment of this application, the data transmission rate is Ntimes the modulation rate of the second digital modulation scheme.High-definition audio data can be transmitted on the BLE physicalchannel at the data transmission rate based on the PDU that is modulatedusing the second digital modulation scheme. In an embodiment of thisapplication, the control layer frame header includes indicationinformation used to indicate a length of the audio data. In this way,the receiving device can verify, based on the indication information forthe audio data in the control layer frame header, whether the receivedaudio data is complete.

In an embodiment of this application, a bandwidth of the BLE physicalchannel is 2 MHz, or a bandwidth of the BLE physical channel is 4 MHz,and the physical channel having the bandwidth of 4 MHz is formed bycombining two adjacent physical channels each having a bandwidth of 2MHz. In this embodiment of this application, the audio data can betransmitted at different transmission rates using different bandwidths.

In an embodiment of this application, the first digital modulationscheme includes the GFSK, and the second digital modulation schemeincludes the DQPSK or the 8DPSK. In this way, compatibility between aBLE mode and an EDR mode is implemented, and power consumption can bereduced while the audio data is transmitted at a high speed.

In an embodiment of this application, a modulation factor of the GFSKranges from 0.45 to 0.55 such that an original hardware device can beused to implement the technical solution in this embodiment of thisapplication, thereby saving hardware resources.

In an embodiment of this application, a codec parameter may be queriedusing the L2CAP, and the codec parameter includes a coding parameter ofthe audio data, and original audio data is encoded based on the codingparameter, to obtain the audio data. Optionally, the audio data may beaudio data on which a process such as encryption or integrity check isperformed.

In an example, if the codec parameter has an index of 0 and is indicatedby 0, it indicates that the coding parameter supports a sampling rate16000 of 16 bits, or if the codec parameter has an index of 1 and isindicated by 1, it indicates that the coding parameter supports asampling rate 32000 of 16 bits.

In this embodiment of this application, the coding parameter is queriedusing the L2CAP, and the original audio data is encoded, to ensurenormal audio play.

FIG. 14 is a schematic flowchart of an audio data transmission methodaccording to another embodiment of the present application. Thisembodiment of this application may be performed by a receiving device.The audio data transmission method further includes the following steps.

S1401. Receive an audio data packet on a BLE physical channel, where theaudio data packet includes a physical layer frame header and a PDU.

The receiving device may receive, on the BLE physical channel, the audiodata packet sent by a sending device, where a bandwidth of the BLEphysical channel is 2 MHz or 4 MHz.

S1402. Demodulate the physical layer frame header using a first digitalmodulation scheme, and demodulate the PDU using a second digitalmodulation scheme, to obtain audio data, where a value of a modulationrate of the first digital modulation scheme is equal to a value of adata transmission rate, and a value of a modulation rate of the seconddigital modulation scheme is less than the value of the datatransmission rate.

The receiving device demodulates the physical layer frame header of theaudio data packet using the first digital modulation scheme, anddemodulates the PDU of the audio data packet using the second digitalmodulation scheme, to obtain the audio data.

In an example, the physical layer frame header is modulated based onGFSK, that is, the physical layer frame header of the audio data packetmay be demodulated using the GFSK.

The PDU of the audio data packet is demodulated using the second digitalmodulation scheme, to obtain the audio data. In an example, the seconddigital modulation scheme is DQPSK or 8DPSK, and the PDU of the audiodata packet is demodulated using the DQPSK or the 8DPSK, to obtain theaudio data.

In this embodiment of this application, the audio data packet isreceived on the BLE physical channel, the physical layer frame header isdemodulated using the first digital modulation scheme, and the PDU isdemodulated using the second digital modulation scheme. The modulationrate of the modulation scheme for the PDU is lower than the datatransmission rate, that is, a same symbol can carry more bits, therebyincreasing an audio data transmission rate, and supporting transmissionof high-definition audio data. In an embodiment of this application, thereceiving device may receive a modulation scheme identifier of the BLEphysical channel. In this way, the receiving device may learn, based onthe modulation scheme identifier, that the physical layer frame headeruses the first digital modulation scheme and the PDU uses the seconddigital modulation scheme, to successfully demodulate the audio data.

In an embodiment of this application, when the receiving device receivesor does not receive the audio data, an acknowledgement message needs tobe returned to the sending device, where the acknowledgement message isused to indicate a receiving status of the audio data. For example, thereceiving status of the audio data includes that the audio data isalready received and/or the audio data is not received.

In an example, a BLE empty packet may be used, that is, the BLE emptypacket is returned to the sending device, to indicate the receivingstatus of the audio data. Because the BLE empty packet uses a GFSKmodulation scheme, an anti-interference capability is strong, therebyfacilitating receiving by the sending device.

FIG. 15 is a schematic structural diagram of an audio data transmissiondevice according to an embodiment of this application. The audio datatransmission device corresponds to the audio data transmission method inFIG. 13. The audio data transmission device in FIG. 15 further includesan audio source device 1501, a baseband processor 1502, and atransmitter 1503.

An audio source device 1501 sends audio data to a baseband processor1502, the baseband processor 1502 encapsulates a PDU of the audio data,and then the transmitter 1503 sends an audio data packet.

The audio source device 1501 sends the audio data to the basebandprocessor.

The baseband processor 1502 encapsulates, based on a physical layerframe header, the PDU including the audio data, to obtain the audio datapacket, where a physical layer frame header is modulated using a firstdigital modulation scheme, the PDU is modulated using a second digitalmodulation scheme, a value of a modulation rate of the first digitalmodulation scheme is equal to a value of a data transmission rate, and avalue of a modulation rate of the second digital modulation scheme isless than the value of the data transmission rate.

The transmitter 1503 sends the audio data packet on a BLE physicalchannel at the data transmission rate.

For example, the audio source device 1501 may be a power amplifier, amultimedia console, a digital audio mixer, an audio sampling card, asynthesizer, or the like.

In this embodiment of this application, the physical layer frame headeris modulated using the first digital modulation scheme, and the PDU ismodulated using the second digital modulation scheme. Because thephysical layer frame header and the PDU are modulated using twodifferent modulation schemes, the modulation rate of the modulationscheme for the PDU is lower than the data transmission rate, that is, asame symbol can carry more bits, thereby increasing an audio datatransmission rate. Therefore, transmission of high-definition audio datacan be supported.

In this embodiment of this application, the data transmission rate maybe N times the modulation rate of the second digital modulation scheme,where N is an integer greater than 1.

In this embodiment of this application, the PDU includes a control layerframe header and a payload, the payload is used to carry the audio data,and the control layer frame header includes indication information usedto indicate a length of the audio data.

In this embodiment of this application, a bandwidth of the BLE physicalchannel is 2 MHz, or a bandwidth of the BLE physical channel is 4 MHz,and the physical channel having the bandwidth of 4 MHz is formed bycombining two adjacent physical channels each having a bandwidth of 2MHz.

In this embodiment of this application, the first digital modulationscheme may include GFSK, and the second digital modulation scheme mayinclude DQPSK or 8DPSK.

In this embodiment of this application, a modulation factor of the GFSKranges from 0.45 to 0.55, that is, the modulation factor of the GFSK isgreater than or equal to 0.45, and less than or equal to 0.55.

In this embodiment of this application, the audio source device 1501further includes an audio codec 15011. The audio codec 15011 isconfigured to generate a modulation scheme identifier of the BLEphysical channel. The baseband processor 1502 may determine, based onthe modulation scheme identifier, the modulation scheme used by the PDU.In this way, the baseband processor 1502 of an audio sending device canmodulate the physical layer frame header and the PDU using thedetermined modulation schemes. Further, the transmitter 1503 sends themodulation scheme identifier of the physical channel to a receivingdevice such that the receiving device can demodulate the physical layerframe header and the PDU using corresponding modulation schemes.

In this embodiment of this application, the audio codec 15011 queries acodec parameter using the L2CAP, where the codec parameter includes acoding parameter of the audio data. Further, the codec 15011 encodesoriginal audio data based on the coding parameter, to obtain the audiodata. The coding parameter is queried using the L2CAP, and the originalaudio data is encoded, to ensure normal audio play.

FIG. 16 is a schematic structural diagram of a receiving deviceaccording to an embodiment of this application, where an audio datatransmission device corresponds to the audio data transmission method inFIG. 14.

The audio data transmission device in FIG. 16 further includes areceiver 1601, a baseband processor 1602, and an audio receiving device1603.

The receiver 1601 receives an audio data packet on a BLE physicalchannel, the baseband processor 1602 demodulates the audio data packet,to obtain audio data, and the audio receiving device 1603 receives theaudio data sent by the baseband processor 1602.

The receiver 1601 receives the audio data packet on the BLE physicalchannel, where the audio data packet includes a physical layer frameheader and a PDU.

The baseband processor 1602 demodulates the physical layer frame headerusing a first digital modulation scheme, and demodulates the PDU using asecond digital modulation scheme, to obtain audio data carried in apayload, where a value of a modulation rate of the first digitalmodulation scheme is equal to a value of a data transmission rate, and avalue of a modulation rate of the second digital modulation scheme isless than the value of the data transmission rate.

The audio receiving device 1603 receives the audio data from thebaseband processor 1602.

In this embodiment of this application, the audio data packet isreceived on the BLE physical channel, the physical layer frame header isdemodulated using the first digital modulation scheme, and the PDU isdemodulated using the second digital modulation scheme. The modulationrate of the modulation scheme for the PDU is lower than the datatransmission rate, that is, a same symbol can carry more bits, therebyincreasing an audio data transmission rate, and supporting transmissionof high-definition audio data. In an embodiment of this application, theaudio receiving device 1603 further includes an audio codec 16031.

The receiver 1601 is configured to receive a modulation schemeidentifier of the BLE physical channel.

The audio codec 16031 is configured to determine, based on themodulation scheme identifier, that the physical layer frame header usesthe first digital modulation scheme, and determine, based on themodulation scheme identifier, that the PDU uses the second digitalmodulation scheme.

In this way, the first digital modulation scheme and the second digitalmodulation scheme can be determined based on the modulation schemeidentifier, and then the audio data can be successfully demodulated.

In an embodiment of this application, a data transmission rate is Ntimes the modulation rate of the second digital modulation scheme, whereN is an integer greater than 1.

In an embodiment of this application, when the receiver 1601 receives ordoes not receive the audio data, an acknowledgement message needs to bereturned to the sending device, where the acknowledgement message isused to indicate a receiving status of the audio data. For example, thereceiving status of the audio data includes that the audio data isalready received and/or the audio data is not received.

In an example, a BLE empty packet is used, that is, the BLE empty packetis returned to the sending device, to indicate the receiving status ofthe audio data. Because the BLE empty packet uses the GFSK modulationscheme, an anti-interference capability is strong, thereby facilitatingreceiving by the sending device.

FIG. 17 is an example diagram of a hardware architecture fortransmitting audio data according to an embodiment of this application.As shown in FIG. 17, a computing device 1700 includes an input device1701, an input interface 1702, a processor 1703, a memory 1704, anoutput interface 1705, and an output device 1706.

The input interface 1702, the processor 1703, the memory 1704, and theoutput interface 1705 are connected to each other using a bus 1710. Theinput device 1701 and the output device 1706 are connected to the bus1710 by respectively using the input interface 1702 and the outputinterface 1705, to connect to another component of the computing device1700.

Specifically, the input device 1701 receives external input information,and transmits the input information to the processor 1703 using theinput interface 1702. The processor 1703 processes the input informationaccording to a computer executable instruction stored in the memory1704, to generate output information, temporarily or permanently storesthe output information in the memory 1704, and then transmits the outputinformation to the output device 1706 through the output interface 1705.The output device 1706 outputs the output information to the outside ofthe computing device 1700 for use by a user.

The computing device 1700 may perform the steps in the foregoing audiodata transmission method in this application.

The processor 1703 may be one or more central processing units (CPU).When the processor 1701 or the processor 1701 is one CPU, the CPU may bea single-core CPU or a multi-core CPU.

The memory 1704 may be but is not limited to one or more of a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM), a compact disc read-only memory (CD-ROM), ahard disk, and the like. The memory 1704 is configured to store programcode.

All or some of the foregoing embodiments may be implemented usingsoftware, hardware, firmware, or any combination thereof. When some orall of the foregoing embodiments are implemented in a form of a computerprogram product, the computer program product includes one or morecomputer instructions. When the computer program instructions are loadedand executed on a computer, the procedure or functions according to theembodiments of this application are all or partially generated. Thecomputer may be a general-purpose computer, a special-purpose computer,a computer network, or other programmable apparatuses. The computerinstructions may be stored in a computer-readable storage medium or maybe transmitted from a computer-readable storage medium to anothercomputer-readable storage medium. For example, the computer instructionsmay be transmitted from a website, a computer, a server, or a datacenter to another website, computer, server, or data center in a wired(for example, a coaxial cable, an optical fiber, or a digital subscriberline (DSL)) or wireless (for example, infrared, radio, or microwave)manner. The computer-readable storage medium may be any usable mediumaccessible by a computer, or a data storage device, such as a server ora data center, integrating one or more usable media. The usable mediummay be a magnetic medium (for example, a floppy disk, a hard disk, or amagnetic tape), an optical medium (for example, a digital versatile disc(DVD)), a semiconductor medium (for example, a solid-state drive (SSD)),or the like.

The embodiments in this specification are all described in a progressivemanner. For same or similar parts in the embodiments, reference may bemade between these embodiments, and each embodiment focuses on adifference from other embodiments. Especially, apparatus and systemembodiments are basically similar to the method embodiments, andtherefore are described briefly, for related parts, reference may bemade to descriptions in the method embodiments.

What is claimed is:
 1. An audio data transmission method, comprising:encapsulating, based on a physical layer frame header, a protocol dataunit (PDU) comprising audio data to obtain an audio data packet, whereinthe physical layer frame header is modulated using a first digitalmodulation scheme, wherein a first modulation rate of the first digitalmodulation scheme is equal to a value of a data transmission rate ofaudio data transmission, wherein the PDU is modulated using a seconddigital modulation scheme, wherein a second modulation rate of thesecond digital modulation scheme is less than the value of the datatransmission rate, wherein the data transmission rate is N times thesecond modulation rate, and wherein N is an integer greater than 1; andsending the audio data packet on a BLUETOOTH Low Energy (BLE) physicalchannel at the data transmission rate.
 2. The audio data transmissionmethod of claim 1, further comprising: generating a modulation schemeidentifier of the BLE physical channel; based on the modulation schemeidentifier, determining whether the physical layer frame header uses thefirst digital modulation scheme and determining whether the PDU uses thesecond digital modulation scheme; and sending the modulation schemeidentifier.
 3. The audio data transmission method of claim 1, whereinthe PDU comprises a control layer frame header and a payload, whereinthe payload carries the audio data, and wherein the control layer frameheader comprises indication information that indicates a length of theaudio data.
 4. The audio data transmission method of claim 1, wherein abandwidth of the BLE physical channel is 2 megahertz (MHz).
 5. The audiodata transmission method of claim 1, wherein the first digitalmodulation scheme comprises Gaussian frequency-shift keying (GFSK), andwherein the second digital modulation scheme comprises eitherdifferential quadrature phase-shift keying (DQPSK) or 8-differentialphase-shift keying (8DPSK).
 6. The audio data transmission method ofclaim 5, wherein a modulation factor of the GFSK ranges from 0.45 to0.55.
 7. The audio data transmission method of claim 1, furthercomprising: querying a codec parameter using a logical link control andadaptation protocol (L2CAP), wherein the codec parameter comprises acoding parameter of the audio data; and encoding original audio data toobtain the audio data based on the coding parameter.
 8. The audio datatransmission method of claim 1, wherein a bandwidth of the BLE physicalchannel is 4 megahertz (MHz), and wherein the bandwidth is based on acombination of two adjacent physical channels each having a bandwidth of2 MHz.
 9. The audio data transmission method of claim 1, wherein thesecond digital modulation scheme comprises differential quadraturephase-shift keying (DQPSK), and wherein the data transmission rate istwo times the second modulation rate.
 10. The audio data transmissionmethod of claim 1, wherein the second digital modulation schemecomprises 8-differential phase-shift keying (8DPSK), and wherein thedata transmission rate is three times the second modulation rate.
 11. Anaudio data transmission method, comprising: receiving an audio datapacket on a BLUETOOTH Low Energy (BLE) physical channel, wherein theaudio data packet comprises a physical layer frame header and a protocoldata unit (PDU); demodulating the physical layer frame header using afirst digital modulation scheme, wherein a first modulation rate of thefirst digital modulation scheme is equal to a value of a datatransmission rate of audio data transmission; and demodulating the PDUusing a second digital modulation scheme to obtain audio data, wherein asecond modulation rate of the second digital modulation scheme is lessthan the value of the data transmission rate, wherein the datatransmission rate is N times the second modulation rate, and wherein Nis an integer greater than
 1. 12. The audio data transmission method ofclaim 11, further comprising: receiving a modulation scheme identifierof the BLE physical channel; determining that the physical layer frameheader uses the first digital modulation scheme based on the modulationscheme identifier; and determining that the PDU uses the second digitalmodulation scheme based on the modulation scheme identifier.
 13. Theaudio data transmission method of claim 11, wherein after obtaining theaudio data, the audio data transmission method further comprisesreturning an acknowledgement message indicating a receiving status ofthe audio data.
 14. The audio data transmission method of claim 11,wherein the second digital modulation scheme comprises differentialquadrature phase-shift keying (DQPSK), and wherein the data transmissionrate is two times the second modulation rate.
 15. An audio datatransmission apparatus, comprising: a baseband processor configured to:encapsulate, based on a physical layer frame header, a protocol dataunit (PDU) comprising audio data, to obtain an audio data packet,wherein the physical layer frame header is modulated using a firstdigital modulation scheme, wherein a first modulation rate of the firstdigital modulation scheme is equal to a value of a data transmissionrate, wherein the PDU is modulated using a second digital modulationscheme, wherein a second modulation rate of the second digitalmodulation scheme is less than the value of the data transmission rate,wherein the data transmission rate is N times the second modulationrate, and wherein N is an integer greater than 1; and a transmittercoupled to the baseband processor and configured to send the audio datapacket on a BLUETOOTH Low Energy (BLE) physical channel at the datatransmission rate.
 16. The apparatus of claim 15, wherein the apparatusfurther comprises an audio codec coupled to the baseband processor andconfigured to generate a modulation scheme identifier of the BLEphysical channel, and wherein the baseband processor is furtherconfigured to: based on the modulation scheme identifier, determinewhether the physical layer frame header uses the first digitalmodulation scheme and determine whether the PDU uses the second digitalmodulation scheme, wherein the transmitter is further configured to sendthe modulation scheme identifier.
 17. The apparatus of claim 15, whereinthe PDU comprises a control layer frame header and a payload, whereinthe payload carries the audio data, and wherein the control layer frameheader comprises indication information that indicates a length of theaudio data.
 18. The apparatus of claim 15, wherein a bandwidth of theBLE physical channel is 2 megahertz (MHz).
 19. The apparatus of claim15, wherein a bandwidth of the BLE physical channel is 4 megahertz(MHz), and wherein the bandwidth is based on a combination of twoadjacent physical channels each having a bandwidth of 2 MHz.